/*
 * Copyright (c) 2007-2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 1999-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: ExpandedNameTable.java,v 1.2.4.1 2005/09/15 08:15:06 suresh_emailid Exp $
 */
package com.sun.org.apache.xml.internal.dtm.ref;

import com.sun.org.apache.xml.internal.dtm.DTM;

/**
 * This is a default implementation of a table that manages mappings from
 * expanded names to expandedNameIDs.
 *
 * %OPT% The performance of the getExpandedTypeID() method is very important
 * to DTM building. To get the best performance out of this class, we implement
 * a simple hash algorithm directly into this class, instead of using the
 * inefficient java.util.Hashtable. The code for the get and put operations
 * are combined in getExpandedTypeID() method to share the same hash calculation
 * code. We only need to implement the rehash() interface which is used to
 * expand the hash table.
 */
public class ExpandedNameTable {

    /** Array of extended types for this document   */
    private ExtendedType[] m_extendedTypes;

    /** The initial size of the m_extendedTypes array */
    private static int m_initialSize = 128;

    /** Next available extended type   */
    // %REVIEW% Since this is (should be) always equal
    // to the length of m_extendedTypes, do we need this?
    private int m_nextType;

    // These are all the types prerotated, for caller convenience.
    public static final int ELEMENT = ((int) DTM.ELEMENT_NODE);
    public static final int ATTRIBUTE = ((int) DTM.ATTRIBUTE_NODE);
    public static final int TEXT = ((int) DTM.TEXT_NODE);
    public static final int CDATA_SECTION = ((int) DTM.CDATA_SECTION_NODE);
    public static final int ENTITY_REFERENCE = ((int) DTM.ENTITY_REFERENCE_NODE);
    public static final int ENTITY = ((int) DTM.ENTITY_NODE);
    public static final int PROCESSING_INSTRUCTION = ((int) DTM.PROCESSING_INSTRUCTION_NODE);
    public static final int COMMENT = ((int) DTM.COMMENT_NODE);
    public static final int DOCUMENT = ((int) DTM.DOCUMENT_NODE);
    public static final int DOCUMENT_TYPE = ((int) DTM.DOCUMENT_TYPE_NODE);
    public static final int DOCUMENT_FRAGMENT = ((int) DTM.DOCUMENT_FRAGMENT_NODE);
    public static final int NOTATION = ((int) DTM.NOTATION_NODE);
    public static final int NAMESPACE = ((int) DTM.NAMESPACE_NODE);

    /** Workspace for lookup. NOT THREAD SAFE!
     * */
    ExtendedType hashET = new ExtendedType(-1, "", "");

    /** The array to store the default extended types. */
    private static ExtendedType[] m_defaultExtendedTypes;

    /**
     * The default load factor of the Hashtable.
     * This is used to calcualte the threshold.
     */
    private static float m_loadFactor = 0.75f;

    /**
     * The initial capacity of the hash table. Use a bigger number
     * to avoid the cost of expanding the table.
     */
    private static int m_initialCapacity = 203;

    /**
     * The capacity of the hash table, i.e. the size of the
     * internal HashEntry array.
     */
    private int m_capacity;

    /**
     * The threshold of the hash table, which is equal to capacity * loadFactor.
     * If the number of entries in the hash table is bigger than the threshold,
     * the hash table needs to be expanded.
     */
    private int m_threshold;

    /**
     * The internal array to store the hash entries.
     * Each array member is a slot for a hash bucket.
     */
    private HashEntry[] m_table;

    /**
     * Init default values
     */
    static {
        m_defaultExtendedTypes = new ExtendedType[DTM.NTYPES];

        for (int i = 0; i < DTM.NTYPES; i++) {
            m_defaultExtendedTypes[i] = new ExtendedType(i, "", "");
        }
    }

    /**
     * Create an expanded name table.
     */
    public ExpandedNameTable() {
        m_capacity = m_initialCapacity;
        m_threshold = (int) (m_capacity * m_loadFactor);
        m_table = new HashEntry[m_capacity];

        initExtendedTypes();
    }

    /**
     *  Initialize the vector of extended types with the
     *  basic DOM node types.
     */
    private void initExtendedTypes() {
        m_extendedTypes = new ExtendedType[m_initialSize];
        for (int i = 0; i < DTM.NTYPES; i++) {
            m_extendedTypes[i] = m_defaultExtendedTypes[i];
            m_table[i] = new HashEntry(m_defaultExtendedTypes[i], i, i, null);
        }

        m_nextType = DTM.NTYPES;
    }

    /**
     * Given an expanded name represented by namespace, local name and node type,
     * return an ID.  If the expanded-name does not exist in the internal tables,
     * the entry will be created, and the ID will be returned.  Any additional
     * nodes that are created that have this expanded name will use this ID.
     *
     * @param namespace The namespace
     * @param localName The local name
     * @param type The node type
     *
     * @return the expanded-name id of the node.
     */
    public int getExpandedTypeID(String namespace, String localName, int type) {
        return getExpandedTypeID(namespace, localName, type, false);
    }

    /**
     * Given an expanded name represented by namespace, local name and node type,
     * return an ID.  If the expanded-name does not exist in the internal tables,
     * the entry will be created, and the ID will be returned.  Any additional
     * nodes that are created that have this expanded name will use this ID.
     * <p>
     * If searchOnly is true, we will return -1 if the name is not found in the
     * table, otherwise the name is added to the table and the expanded name id
     * of the new entry is returned.
     *
     * @param namespace The namespace
     * @param localName The local name
     * @param type The node type
     * @param searchOnly If it is true, we will only search for the expanded name.
     * -1 is return is the name is not found.
     *
     * @return the expanded-name id of the node.
     */
    public int getExpandedTypeID(String namespace, String localName, int type, boolean searchOnly) {
        if (null == namespace)
            namespace = "";
        if (null == localName)
            localName = "";

        // Calculate the hash code
        int hash = type + namespace.hashCode() + localName.hashCode();

        // Redefine the hashET object to represent the new expanded name.
        hashET.redefine(type, namespace, localName, hash);

        // Calculate the index into the HashEntry table.
        int index = hash % m_capacity;
        if (index < 0)
            index = -index;

        // Look up the expanded name in the hash table. Return the id if
        // the expanded name is already in the hash table.
        for (HashEntry e = m_table[index]; e != null; e = e.next) {
            if (e.hash == hash && e.key.equals(hashET))
                return e.value;
        }

        if (searchOnly) {
            return DTM.NULL;
        }

        // Expand the internal HashEntry array if necessary.
        if (m_nextType > m_threshold) {
            rehash();
            index = hash % m_capacity;
            if (index < 0)
                index = -index;
        }

        // Create a new ExtendedType object
        ExtendedType newET = new ExtendedType(type, namespace, localName, hash);

        // Expand the m_extendedTypes array if necessary.
        if (m_extendedTypes.length == m_nextType) {
            ExtendedType[] newArray = new ExtendedType[m_extendedTypes.length * 2];
            System.arraycopy(m_extendedTypes, 0, newArray, 0, m_extendedTypes.length);
            m_extendedTypes = newArray;
        }

        m_extendedTypes[m_nextType] = newET;

        // Create a new hash entry for the new ExtendedType and put it into
        // the table.
        HashEntry entry = new HashEntry(newET, m_nextType, hash, m_table[index]);
        m_table[index] = entry;

        return m_nextType++;
    }

    /**
     * Increases the capacity of and internally reorganizes the hashtable,
     * in order to accommodate and access its entries more efficiently.
     * This method is called when the number of keys in the hashtable exceeds
     * this hashtable's capacity and load factor.
     */
    private void rehash() {
        int oldCapacity = m_capacity;
        HashEntry[] oldTable = m_table;

        int newCapacity = 2 * oldCapacity + 1;
        m_capacity = newCapacity;
        m_threshold = (int) (newCapacity * m_loadFactor);

        m_table = new HashEntry[newCapacity];
        for (int i = oldCapacity - 1; i >= 0; i--) {
            for (HashEntry old = oldTable[i]; old != null;) {
                HashEntry e = old;
                old = old.next;

                int newIndex = e.hash % newCapacity;
                if (newIndex < 0)
                    newIndex = -newIndex;

                e.next = m_table[newIndex];
                m_table[newIndex] = e;
            }
        }
    }

    /**
     * Given a type, return an expanded name ID.Any additional nodes that are
     * created that have this expanded name will use this ID.
     *
     * @return the expanded-name id of the node.
     */
    public int getExpandedTypeID(int type) {
        return type;
    }

    /**
     * Given an expanded-name ID, return the local name part.
     *
     * @param ExpandedNameID an ID that represents an expanded-name.
     * @return String Local name of this node, or null if the node has no name.
     */
    public String getLocalName(int ExpandedNameID) {
        return m_extendedTypes[ExpandedNameID].getLocalName();
    }

    /**
     * Given an expanded-name ID, return the local name ID.
     *
     * @param ExpandedNameID an ID that represents an expanded-name.
     * @return The id of this local name.
     */
    public final int getLocalNameID(int ExpandedNameID) {
        // ExtendedType etype = m_extendedTypes[ExpandedNameID];
        if (m_extendedTypes[ExpandedNameID].getLocalName().equals(""))
            return 0;
        else
            return ExpandedNameID;
    }

    /**
     * Given an expanded-name ID, return the namespace URI part.
     *
     * @param ExpandedNameID an ID that represents an expanded-name.
     * @return String URI value of this node's namespace, or null if no
     * namespace was resolved.
     */
    public String getNamespace(int ExpandedNameID) {
        String namespace = m_extendedTypes[ExpandedNameID].getNamespace();
        return (namespace.equals("") ? null : namespace);
    }

    /**
     * Given an expanded-name ID, return the namespace URI ID.
     *
     * @param ExpandedNameID an ID that represents an expanded-name.
     * @return The id of this namespace.
     */
    public final int getNamespaceID(int ExpandedNameID) {
        //ExtendedType etype = m_extendedTypes[ExpandedNameID];
        if (m_extendedTypes[ExpandedNameID].getNamespace().equals(""))
            return 0;
        else
            return ExpandedNameID;
    }

    /**
     * Given an expanded-name ID, return the local name ID.
     *
     * @param ExpandedNameID an ID that represents an expanded-name.
     * @return The id of this local name.
     */
    public final short getType(int ExpandedNameID) {
        //ExtendedType etype = m_extendedTypes[ExpandedNameID];
        return (short) m_extendedTypes[ExpandedNameID].getNodeType();
    }

    /**
     * Return the size of the ExpandedNameTable
     *
     * @return The size of the ExpandedNameTable
     */
    public int getSize() {
        return m_nextType;
    }

    /**
     * Return the array of extended types
     *
     * @return The array of extended types
     */
    public ExtendedType[] getExtendedTypes() {
        return m_extendedTypes;
    }

    /**
     * Inner class which represents a hash table entry.
     * The field next points to the next entry which is hashed into
     * the same bucket in the case of "hash collision".
     */
    private static final class HashEntry {
        ExtendedType key;
        int value;
        int hash;
        HashEntry next;

        protected HashEntry(ExtendedType key, int value, int hash, HashEntry next) {
            this.key = key;
            this.value = value;
            this.hash = hash;
            this.next = next;
        }
    }

}
